This dataset contains experimental data from a number of field experiments with potato in The Netherlands (Van Evert et al., 2011). The data are presented as an SQL dump of a PostgreSQL database (version 8.4.4). An outline of the entity-relationship diagram of the database is given in an accompanying file. Dutch is required to understand some of the column names, because time pressure has prevented translating all column names to English. Views are presented without much comment. You may or may not find them helpful. The database was used in this form by us to perform our analyses and to prepare our publications. The information presented here represents a good-faith effort to preserve and transfer the experimental data from a number of experiments. We realize that the documentation of the meaning of tables and columns could have been better, but this is as complete as we could make it with the available resources. The following researchers and assistants were each involved in one or more of the experiments: * Frits K. van Evert * David A. van der Schans * Willem C.A. van Geel * Hanja Slabbekoorn * Remmie Booij * Jan Nammen Jukema * Bert Meurs * Dik Uenk References: Van Evert F.K., Van der Schans D.A., Malda J.T., Van den Berg W., Van Geel W.C.A., Jukema J.N. (2011) Geleide N-bemesting voor aardappelen op basis van gewasreflectie-metingen: Integratie van sensormetingen in een N-bijmestsysteem. PPO Rapport 423. WUR-PPO, Lelystad.